In order to reduce the power consumption, a mobile terminal apparatus in a standby state uses a high frequency clock signal for a reception operation while using a low frequency clock signal for time management and the likes when it receives a broadcast information signal from a base station, and stops a high frequency clock oscillator used for the reception operation and uses a low frequency clock signal alone when the mobile terminal apparatus is not receiving the broadcast information signal from the base station. The mobile terminal apparatus counts the number of clocks until a reception timing of the next broadcast information signal by using the low frequency clock signal, and activates the high frequency clock oscillator at the point when the number of clocks reaches the reception timing of the broadcast information signal so as to shift to the reception operation (see Patent Document 1, for example).    Patent Document 1: Japanese Patent Laid-Open Publication No. 2000-244351